In known manner, heat treatment of preforms in an oven is followed by transformation of the preforms into bottles in the blower unit, by shaping them by blowing or drawing-blowing in a mold, after which the containers are transferred to a filler and capping unit.
Thus the installation includes, upstream of the filler unit, a production unit preferably including a heat treatment oven and a blower unit.
The filler unit and the production unit, or at least the blower unit, are generally juxtaposed to obtain a unified production installation that is compact and carries out the whole of the production process, up to obtaining finished products.
In such a container production installation, the aim is to reduce by all means necessary the risk of contamination of the containers, which are likely to be filled with products that are more or less sensitive to such risks.
Consequently, it is known to carry out different actions whose only purpose is monitoring and controlling the microbiological quality of the production environment, i.e. eliminating pathogens such as germs, spores, bacteria, etc. that are liable to affect the content of the containers, notably to render them unfit for consumption.
To this end, these actions are not aimed exclusively at decontaminating the containers, but also at decontaminating the preforms from which they are produced and in general decontaminating the installation itself.
The prior art documents cited hereinafter, which should be referred to for more details, illustrate such actions by way of nonlimiting example only.
The document WO-2006/136498 for example describes decontaminating a preform by spraying a jet of sterilizing product vapor that is deposited by condensation on the internal wall of the preform, in the form of a substantially uniform film or mist of sterilizing product, in order to decontaminate said internal wall.
The document WO-2008/049876 also describes decontaminating the external wall of a preform during its heat treatment in an oven by the combined application of infrared radiation and ultraviolet radiation.
The document FR-2.915.127 describes an installation including a protective enclosure delimiting an area inside which is placed a container production unit including a blowing or drawing-blowing molding machined fed by transfer means with preforms previously heat treated in an oven, said installation including a system for blowing filtered air into the enclosure to establish therein an increased pressure in order to limit the risk of contamination of the performs, now containers, in the exit area of the oven.
Of course, these actions may be carried out simultaneously in the same installation to achieve a drastic reduction in the risk of contamination.
In the production process, the operation of filling the container is usually recognized as being the most sensitive in terms of the risk of contamination.
The containers introduced into the filler unit are merely one of the main vectors of contamination, however. As soon as they are present in the direct environment of the containers, from the air to the components of the installation, pathogens are liable in particular to contaminate the interior volume of the container.
This is why, over and above the sterilization and disinfection treatments aimed directly at the product intended to be introduced into the container and the container itself, the filler unit itself is also decontaminated, including a confinement enclosure adapted to isolate it from the surrounding atmosphere and to delimit an area to be sterilized and in which filling is carried out.
Such a filler unit is sometimes referred to as an isolator, a term which, by definition, generally designates any enclosure enabling operation to be carried out with no risk of contamination.
To the second area of the filler unit is sterilized by chemical decontamination, in particular by spraying sterilizing solutions such as sodium hydroxide (NaOH) or hydrogen peroxide (H2O2).
The decontamination of the second area of the filler unit corresponds to a decontamination mode of operation of the installation that precedes and/or succeeds a production mode of operation of the installation.
To be able to operate the filler unit in the decontamination mode, it is necessary to isolate the filler unit from the remainder of the installation and especially from the adjacent blower unit.
Although the components of the filler unit are produced in appropriate materials, such as 316L stainless steel, to resist the chemical aggression of the aforementioned decontamination solutions, this is not the case with those of the blower unit and the adjoining transfer device disposed between these units.
Thus the decontamination solutions are liable to cause undesirable chemical attack, notably corrosion of components of the transfer device and the blower unit, in particular the molds.
In such an installation, each unit therefore has its own enclosure, respectively a protective or first enclosure that delimits a first area in which at least the container blower unit is placed and a confinement or second enclosure that delimits a second sterile area in which at least a finished container filler unit is placed.
The second enclosure at least in part adjoins the first enclosure via a common interface part in which is provided an opening intended to enable transfer of the containers between said enclosures, from the blower unit to the filler unit, when the installation is operating in production mode.
To enable the filler unit to be isolated during operation of the installation in decontamination mode, the installation includes means for selectively shutting off said communication opening between the blower unit and the filler unit, such as a window through part of their respective enclosures.
The means for shutting off the opening are thus intended to be selectively displaced between an open position in which they allow said transfer of containers through the common opening when the installation is operating in production mode and a closed position in which they prevent such transfer, isolating the second enclosure, in particular to carry out the operations of treating the filler unit during operation in decontamination mode.
To transfer containers between the blower unit and the filler unit in production mode, the installation includes at least one transfer device including at least one transfer wheel.
Generally placed in the first area, the transfer wheel is adjacent said opening and has at least one part extending through the opening to transfer the containers. This part of the transfer wheel must be demounted beforehand to enable closing of the opening by the associated shutting off means.
The operation of demounting and then remounting at least part of the transfer wheel necessitates the intervention of an operator who, to carry out this operation, must enter the protection or first enclosure, which in particular is provided with doors for this purpose, in order to enter part of the first area, called the transfer area, in which is placed said transfer wheel that the operator must access to carry out said operations.
The operator carrying out such demounting and remounting operations is then a serious potential vector for the introduction of pathogens into the installation.
The demounting and/or remounting operations are thus particularly sensitive operations in that they carry a non-negligible risk of contaminating the protected working areas of the installation, which risks of contamination are of different orders.
Firstly, on entering the first enclosure from outside the installation in order to demount at least part of the transfer wheel, the operator is initially liable to introduce such pathogens into the first area, to be more precise into the transfer area.
Then, after sterilizing the second area of the filler unit in decontamination mode, the operator must again enter the first enclosure to remount at least said previously demounted part of the transfer wheel, and while doing this the operator is again likely to introduce pathogens into the first area.
The pathogens introduced by the operator into the installation the first time and likewise the second time may then immediately and/or subsequently contaminate all parts of the production unit and therefore the containers produced therein.
The pathogens introduced in this way are very particularly liable to contaminate the sterile second area by airborne transfer from the transfer area of the first part, as air circulates inside the areas delimited by the enclosures.
Consequently, it should be noted that the entry of the operator into the first area is generally speaking always prejudicial at least to the blower unit and that it occurs a first time on demounting part of the transfer wheel and/or a second time on remounting it.
Such introduction of pathogens at the same time as entry of the operator is liable to affect all actions carried out to prevent and in the case of some of them drastically to reduce the risk of contamination referred to above
However, such introduction is equally and more importantly liable to affect the sterile environment of the second area of the filler unit, which then runs into multiple contamination risks.
A first risk of contaminating the filler unit occurs on demounting part of the transfer wheel if pathogens are introduced with the operator, because airborne pathogens may be transferred by the circulating air immediately and for as long as the opening is not shut off.
It will nevertheless be clear that such contamination does not appear critical if such pathogens are destroyed subsequently by the decontamination treatment.
A second risk of contamination of the filler unit occurs during the remounting operation, during which the common interface opening is again open; any pathogens introduced with the operator are then, in exactly the same way, liable to affect the sterile environment of the second area of the filler unit, and notably the containers that will subsequently be filled there in production mode.
Thus the most critical risks of contamination of the filler unit are more particularly, although not exclusively, those linked to the remounting operation if it follows on from decontamination of the second area.
Not exclusively in that pathogens introduced with the operator into the transfer area of the first area during demounting and/or remounting of part of the transfer wheel may also subsequently, and thus after the remounting operation, penetrate the sterile second area of the decontaminated filler unit.
Apart from the risk of effective contamination of the first area, there is then a potential risk of contamination of the sterile second area, simply because of the presence of such agents in the first area.
These pathogens are liable to contaminate the sterile second area either by airborne transfer in the air flowing through the opening or by being transported there by the containers themselves which, in production mode, travel from the first area to the second.